Digital Signal Processing Reference
In-Depth Information
digital video signal could be transformed for displaying in Phase Alternating Line
(PAL) or National Television System Committee (NTSC) format. Moreover, 128MB
DDR SDRAM , 64MB NAND FLASH and 4GB SD card constitute the storage part,
which could basically meet the video data recording and playing requirement of the
proposed system. The peripheral interface module mainly consists of wireless net-
work and Ethernet chip, serial device and interface (RS485) and Universal Serial Bus
(USB) ports
et al
.
3.2.2 Software Platform Design
The Android-based software architecture is shown in Fig. 2(b). Generally, we divide
it into three levels, the system and driver level, the intermediate level, and the applica-
tion level. The system and driver lever provides the basic driver and Linux-based
system kernel support. The intermediate level mainly consists of the run-time library,
while the application level contains the independent Java-based application. We re-
serve some basic applications which are already included in Android system, so that
the functions of wearable subsystem could be further extended.
(a) Hardware platform (b) Software platform
Fig. 2.
Architecture of wearable wireless communication subsystem
4
Basic Function Analysis
Main functions of the proposed system are presented in this section, including HD
video processing, V2IP communication and physiological signal processing.
4.1
HD Video Processing in Portable Subsystem
In a common video processing platform like a personal computer (PC), video data
compression is often conducted by software, which means the encoding and decoding
process is finished by the central processing unit (CPU) of the system, which also
provides computation service for other application. The software-based encoding and
decoding process has the following disadvantages: firstly, it occupies most parts of
CPU resources and memory during the coding process, which could create negative
influence on the parallel computation performance of the system; secondly, the cost of
